Optical semiconductor device having pre-molded leadframe with window and method therefor

ABSTRACT

A semiconductor device is made by providing a semiconductor die having an optically active area, providing a leadframe or pre-molded laminated substrate having a plurality of contact pads and a light transmitting material disposed between the contact pads, attaching the semiconductor die to the leadframe so that the optically active area is aligned with the light transmitting material to provide a light transmission path to the optically active area, and disposing an underfill material between the semiconductor die and leadframe. The light transmitting material includes an elevated area to prevent the underfill material from blocking the light transmission path. The elevated area includes a dam surrounding the light transmission path, an adhesive ring, or the light transmission path itself can be the elevated area. An adhesive ring can be disposed on the dam. A filler material can be disposed between the light transmitting material and contact pads.

CLAIM OF DOMESTIC PRIORITY

The present application is a division of U.S. patent application Ser.No. 13/419,242, now U.S. Pat. No. 8,586,422, filed Mar. 13, 2012, whichis a continuation of U.S. patent application Ser. No. 12/044,688, nowU.S. Pat. No. 8,138,027, filed Mar. 7, 2008, which applications areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates in general to semiconductor devices and,more particularly, to an optical semiconductor device and method ofpre-molding a leadframe with a window.

BACKGROUND OF THE INVENTION

Semiconductor devices are found in many products in the fields ofentertainment, communications, networks, computers, and householdmarkets. Semiconductor devices are also found in military, aviation,automotive, industrial controllers, and office equipment. Thesemiconductor devices perform a variety of electrical functionsnecessary for each of these applications.

The manufacture of semiconductor devices involves formation of a waferhaving a plurality of die. Each semiconductor die contains hundreds orthousands of transistors and other active and passive devices performinga variety of electrical functions. For a given wafer, each die from thewafer typically performs the same electrical function. Front-endmanufacturing generally refers to formation of the semiconductor deviceson the wafer. The finished wafer has an active side containing thetransistors and other active and passive components. Back-endmanufacturing refers to cutting or singulating the finished wafer intothe individual die and then packaging the die for structural support andenvironmental isolation.

One goal of semiconductor manufacturing is to produce a package suitablefor faster, reliable, smaller, and higher-density integrated circuits(IC) at lower cost. Flip chip packages or wafer level chip scalepackages (WLCSP) are ideally suited for ICs demanding high speed, highdensity, and greater pin count. Flip chip style packaging involvesmounting the active side of the die facedown toward a chip carriersubstrate or printed circuit board (PCB). The electrical and mechanicalinterconnect between the active devices on the die and conduction trackson the carrier substrate is achieved through a solder bump structurecomprising a large number of conductive solder bumps or balls. Thesolder bumps are formed by a reflow process applied to solder materialdeposited on contact pads which are disposed on the semiconductorsubstrate. The solder bumps are then soldered to the carrier substrate.The flip chip semiconductor package provides a short electricalconduction path from the active devices on the die to the carriersubstrate in order to reduce signal propagation, lower capacitance, andachieve overall better circuit performance.

Some semiconductor devices have optically active regions. The opticaldevices react to light and generate electrical signals in responsethereto. The electrical signals are processed by other active andpassive circuits within the semiconductor device. The light must passthrough the semiconductor package to reach the optical devices. In somedevices, the light passes through an opening in the substrate, such asdescribed in U.S. Pat. No. 6,765,236. The process of forming the openingin the substrate and confirming alignment for the passage of light tothe optical devices adds manufacturing steps and complexity. Inaddition, the semiconductor package typically has underfill material andmolding compound for structural integrity and environmental protection.Care must be taken when applying the underfill material and moldingcompound to avoid blocking the passage of light to the optical devices.

A need exists for a simple process to make optical semiconductorpackages without interfering with the passage of light to the opticaldevices.

SUMMARY OF THE INVENTION

In one embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a semiconductordie including an optically active area, providing a substrate includinga light transmitting region, disposing the semiconductor die over thesubstrate to align the light transmitting region with the opticallyactive area, and depositing an encapsulant over the semiconductor dieand substrate. An elevated area of the substrate blocks the encapsulantto maintain light transmission through the light transmitting region tothe optically active area of the semiconductor die.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a semiconductordie including an optically active area, providing a substrate includinga light transmitting region, and disposing the semiconductor die overthe substrate to align the light transmitting region of the substratewith the optically active area of the semiconductor die.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a semiconductordie, providing a substrate including a light transmitting region, anddisposing the semiconductor die over the substrate.

In another embodiment, the present invention is a method of making asemiconductor device comprising providing a substrate including anelevated area and a light transmitting region disposed within thesubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a-1c illustrate a pre-molded leadframe and window with anoptional dam and elevated window;

FIGS. 2a-2c illustrate a laminated leadframe with a window and optionaldam and elevated window;

FIG. 3 illustrates a pre-molded leadframe with a window and offsetcontact pads;

FIGS. 4a-4b illustrate a pre-molded leadframe having a window and fillermaterial surrounding the contact pads with optional dam;

FIGS. 5a-5b illustrate a pre-molded leadframe with B-stage adhesive ringand window and optional dam;

FIG. 6 is an optical semiconductor die connected to a pre-moldedleadframe with a window;

FIG. 7 is an optical semiconductor die connected to a pre-moldedleadframe with a window and clear encapsulant surrounding the die;

FIG. 8 is an optical semiconductor die connected to a pre-moldedleadframe with a window and having underfill material around solderbump;

FIG. 9 is an optical semiconductor die connected to a pre-moldedleadframe with a window having notches to contain underfill material;

FIG. 10 is an optical semiconductor die connected to a leadframe andclear encapsulant surrounding the die;

FIG. 11 is an optical semiconductor die connected to a pre-moldedleadframe with a window having a dam to contain underfill material;

FIG. 12 is an optical semiconductor die connected to a pre-moldedleadframe with a window having a dam and B-stage ring to contain moldingcompound;

FIG. 13 is an optical semiconductor die connected to a pre-moldedleadframe with a B-stage ring to contain molding compound;

FIG. 14 is an optical semiconductor die connected to a pre-moldedleadframe with an elevated window to contain molding compound;

FIG. 15 is an optical semiconductor die connected to a pre-moldedleadframe with an elevated window to contain molding compound;

FIG. 16 is an optical semiconductor die connected to a pre-moldedleadframe with an elevated window and clear underfill material;

FIG. 17 is an optical semiconductor die connected to a pre-moldedleadframe with an elevated window and clear adhesive;

FIG. 18 is an optical semiconductor die connected to a pre-moldedleadframe with convex lens having a dam to contain underfill material;

FIG. 19 is an optical semiconductor die connected to a pre-moldedleadframe having filler material and embedded glass;

FIG. 20 is an optical semiconductor die connected to a pre-moldedleadframe having filler material and embedded glass and clear underfillmaterial;

FIG. 21 is an optical semiconductor die connected to a pre-moldedleadframe with an elevated window and embedded glass;

FIG. 22 is an optical semiconductor die connected to a pre-moldedleadframe having offset contact pads and a window and B-stage ring;

FIG. 23 is an optical semiconductor die connected to a pre-moldedleadframe having offset contact pads and an elevated window and clearunderfill material;

FIG. 24 is an optical semiconductor die connected to a pre-moldedlaminated substrate with a window and B-stage ring;

FIG. 25 is an optical semiconductor die connected to a pre-moldedlaminated substrate with a window having a dam to contain underfillmaterial;

FIG. 26 is an optical semiconductor die connected to a pre-moldedleadframe by wire bonds and having a window with a dam and B-stage ringover the dam; and

FIG. 27 is an optical semiconductor die connected to a pre-moldedleadframe by wire bonds and having a window and B-stage ring to containencapsulant.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention is described in one or more embodiments in thefollowing description with reference to the Figures, in which likenumerals represent the same or similar elements. While the invention isdescribed in terms of the best mode for achieving the invention'sobjectives, it will be appreciated by those skilled in the art that itis intended to cover alternatives, modifications, and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims and their equivalents as supported by the followingdisclosure and drawings.

The manufacture of semiconductor devices involves formation of a waferhaving a plurality of die. Each die contains hundreds or thousands oftransistors and other active and passive devices performing one or moreelectrical functions. For a given wafer, each die from the wafertypically performs the same electrical function. Front-end manufacturinggenerally refers to formation of the semiconductor devices on the wafer.The finished wafer has an active side containing the transistors andother active and passive components. Back-end manufacturing refers tocutting or singulating the finished wafer into the individual die andthen packaging the die for structural support and/or environmentalisolation.

A semiconductor wafer generally includes an active surface havingsemiconductor devices disposed thereon, and a backside surface formedwith bulk semiconductor material, e.g., silicon. The active side surfacecontains a plurality of semiconductor die. The active surface is formedby a variety of semiconductor processes, including layering, patterning,doping, and heat treatment. In the layering process, semiconductormaterials are grown or deposited on the substrate by techniquesinvolving thermal oxidation, nitridation, chemical vapor deposition,evaporation, and sputtering. Photolithography involves the masking ofareas of the surface and etching away undesired material to formspecific structures. The doping process injects concentrations of dopantmaterial by thermal diffusion or ion implantation.

Semiconductor die are typically attached to a substrate or leadframe forstructural support and interconnection. In FIG. 1a , leadframe 30 isadapted for receiving a semiconductor die. In one embodiment, leadframe30 is an un-singulated flat pre-molded laminated substrate. Leadframe 30includes a dam bar 32 and a plurality of fingers or contact pads 34.Leadframe 30 is made with gold, silver, nickel, platinum, copper, copperalloys (including one or more elements of nickel, iron, zinc, tin,chromium, silver, and phosphorous), or other suitable materials. A clearpre-molded window 36 is disposed in an interior portion of leadframe 30.Window 36 is made with an optical grade resin compound or other suitablelight transmitting material. Window 36 is capable of passing light fromexternal sources to semiconductor device 10.

FIG. 1b shows an alternative embodiment for window 36 with dam 40 formedaround a perimeter of the active window. Dam 40 is made with the samematerial as window 36. Dam 40 can be stepped or contoured to operate asa retaining or separation structure and provide pre-mold interlocking asdiscussed below. In another embodiment, FIG. 1c shows window 36 with anelevated portion (window) 42. Again, the elevated window 42 operates asa separation structure as discussed below.

FIG. 2a shows leadframe 50 is a flat pre-molded laminate print circuitboard (PCB) substrate 52 with a plurality of vias. The vias are filledwith conductive material to form lands 54. A clear pre-molded window 56is disposed in an interior portion of leadframe 50. Window 56 is madewith an optical grade resin compound or other suitable lighttransmitting material. Window 56 is capable of passing light fromexternal sources to semiconductor device 10.

FIG. 2b shows an alternative embodiment for window 56 with dam 60 formedaround a perimeter of the active window. Dam 60 can be made with thesame material as window 56. Dam 60 operates as a retaining or separationstructure. In another embodiment, FIG. 2c shows window 56 with anelevated portion (window) 62. Again, the elevated window 62 operates asa separation structure.

In FIG. 3, leadframe 70 is an un-singulated flat pre-molded substrate.Leadframe 70 includes a dam bar 72 and a plurality of fingers or contactpads 74. Leadframe 70 is made with gold, silver, nickel, platinum,copper, copper alloys (including one or more elements of nickel, iron,zinc, tin, chromium, silver, and phosphorous), or other suitablematerials. Adjacent ones of the contact pads 74 have different lengthsand are offset to increase packing density. A clear pre-molded window 76is disposed in an interior portion of leadframe 70. Window 76 is madewith an optical grade resin compound or other suitable lighttransmitting material. Window 76 is capable of passing light fromexternal sources to semiconductor device 10.

In FIG. 4a , leadframe 80 is an un-singulated flat pre-molded substrate.Leadframe 80 includes a dam bar 82 and a plurality of fingers or contactpads 84. Leadframe 80 is made with gold, silver, nickel, platinum,copper, copper alloys (including one or more elements of nickel, iron,zinc, tin, chromium, silver, and phosphorous), or other suitablematerials. A pre-mold opaque filler material 86 such as an epoxy moldingcompound or liquid crystal polymer is disposed between contact pads 84.A clear pre-molded window 88 is embedded in an interior portion ofleadframe 80 and sealed to filler material 86 with an adhesive. Window88 is made with an optical grade resin compound or other suitable lighttransmitting material. Window 88 is capable of passing light fromexternal sources to semiconductor device 10. FIG. 4b shows analternative embodiment for leadframe 80 with dam 90 formed around aperimeter of window 88, using the same filler material 86. Dam 90operates as a retaining or separation structure. The filler material 86and window 88 also work with a laminate substrate as described in FIGS.2a -2 c.

In FIG. 5a , leadframe 100 is an un-singulated flat pre-moldedsubstrate. Leadframe 100 includes a dam bar 102 and a plurality offingers or contact pads 104. Leadframe 100 is made with gold, silver,nickel, platinum, copper, copper alloys (including one or more elementsof nickel, iron, zinc, tin, chromium, silver, and phosphorous), or othersuitable materials. A clear pre-molded window 106 is disposed in aninterior portion of leadframe 100. Window 106 is made with an opticalgrade resin compound or other suitable light transmitting material.Window 106 is capable of passing light from external sources tosemiconductor device 10. An adhesive ring 108 is disposed around aperimeter of window 106. Ring 108 is made with ultraviolet (UV)irradiation B-stage adhesive such as epoxy acrylate blends, thixotropicpastes, or other suitable material. Ring 108 operates as a retaining orseparation structure. In another embodiment, FIG. 5b shows dam 110formed around a perimeter of window 106. An adhesive ring 112 isdisposed on dam 110. The combination of dam 110 and ring 112 operates asa retaining or separation structure.

FIG. 6 illustrates pre-molded leadframe 120 with window 122, e.g., anyleadframe discussed in FIGS. 1-5. An optically active semiconductor dieor image sensor die 124 with optically active area 126 is mechanicallyand electrically attached to leadframe 120 with solder bumps 128. Ineach case described below, the pre-molded leadframe with windowsimplifies the manufacturing process. The leadframe and window are apre-molded unit. Window 122 is aligned to optically active area 126 toprovide a light transmission path. The optical devices react to lightand generate electrical signals in response thereto. The electricalsignals are processed by other active and passive circuits within thesemiconductor die.

Solder bumps 128 are formed by depositing an electrically conductivesolder material over contact pads 129 using an evaporation, electrolyticplating, electroless plating, ball drop, or screen printing process. Thesolder material can be any metal or electrically conductive material,e.g., tin, lead, nickel, gold, silver, copper, bismuthinite and alloysthereof. The solder material is reflowed by heating the conductivematerial above its melting point to form spherical balls or bumps 128.In some applications, solder bumps 128 are reflowed a second time toimprove electrical contact to contact pad 129. An additional under bumpmetallization can optionally be formed under solder bumps 128. Anoptical grade underfill material 130 is disposed under semiconductor die124. Solder bumps 128 provide electrical interconnect for semiconductordie 124, as well as other semiconductor devices or external electricalconnections.

A molding compound 132 is disposed over leadframe 120 and semiconductordie 124. Molding compound 132 can be made with epoxide resins, silica,cresol novolac epoxy, phenol novolac, antimony, bromide, or carbon.

FIG. 7 illustrates pre-molded leadframe 120 with window 122, e.g., anyleadframe discussed in FIGS. 1-5. A semiconductor die 124 with opticallyactive area 126 is mechanically and electrically attached to leadframe120 with solder bumps 128. An optical grade material 134 is disposedabove and below semiconductor die 124.

FIG. 8 illustrates pre-molded leadframe 120 with window 122, e.g., anyleadframe discussed in FIGS. 1-5. A semiconductor die 124 with opticallyactive area 126 is mechanically and electrically attached to leadframe120 with solder bumps 128. An underfill material 136 is disposed undersemiconductor die 124 around solder bumps 128, but does not occupy area138 above window 122. Area 138 is devoid of material. The underfillmaterial 136 can be epoxy, polymeric material, film, or othernon-conductive material. A molding compound 140 is disposed overleadframe 120 and semiconductor die 124. Molding compound 140 can bemade with epoxide resins, silica, cresol novolac epoxy, phenol novolac,antimony, bromide, or carbon.

FIG. 9 illustrates pre-molded leadframe 120 with window 122, e.g., anyleadframe discussed in FIGS. 1-5. A semiconductor die 124 with opticallyactive area 126 is mechanically and electrically attached to leadframe120 with solder bumps 128. An underfill material 136 is disposed undersemiconductor die 124 around solder bumps 128, but does not occupy area138 above window 122. Area 138 is devoid of material. The underfillmaterial 136 can be epoxy, polymeric material, film, or othernon-conductive material. In this embodiment, window 122 includes notches142 to prevent the underfill material from encroaching onto window 122.Excess underfill material 136 is captured and held in notches 142, whichkeeps window 122 free to pass maximum light. The notches 142 prevent theunderfill material from blocking the light transmission path throughwindow 122. A molding compound 140 is disposed over leadframe 120 andsemiconductor die 124.

In FIG. 10, a leadframe 144 is shown without the pre-molded window. Asemiconductor die 146 with optically active area 148 is mechanically andelectrically attached to leadframe 144 with solder bumps 150. Anencapsulant 152, such as a clear epoxy molding compound, is disposedabove and below semiconductor die 146 to pass light through leadframe144 to optically active area 148.

FIG. 11 illustrates pre-molded leadframe 160 with window 162. Asemiconductor die 164 with optically active area 166 is mechanically andelectrically attached to leadframe 160 with solder bumps 168. Window 162is aligned to optically active area 166 to provide a light transmissionpath. An underfill material 170 is disposed under semiconductor die 164around solder bumps 168, but does not occupy area 172 above window 162.Area 172 is devoid of material. In this embodiment, window 162 includesdam 174, such as shown in FIGS. 1b and 2b , to prevent the underfillmaterial from encroaching onto window 162. Excess underfill material 170is held back by dam 174, which keeps window 162 free to pass maximumlight. The dam 174 prevents the underfill material from blocking thelight transmission path through window 162. The underfill material 170can be epoxy, polymeric material, film, or other non-conductivematerial. Solder bumps 168 can be sized to create a gap between dam 174and semiconductor die 164. A molding compound 176 is disposed overleadframe 160 and semiconductor die 164. Molding compound 176 can bemade with epoxide resins, silica, cresol novolac epoxy, phenol novolac,antimony, bromide, or carbon.

FIG. 12 illustrates pre-molded leadframe 160 with window 162. Asemiconductor die 164 with optically active area 166 is mechanically andelectrically attached to leadframe 160 with solder bumps 168. In thisembodiment, window 162 includes dam 174 to prevent any material fromencroaching onto window 162. A B-stage adhesive ring 178 is disposed ontop of dams 174, as shown in FIG. 5b , and adheres to semiconductor die164. Adhesive ring 178 can be pre-applied or dispensed during theprocess. A molding compound 176 is disposed over leadframe 160 andsemiconductor die 164. The molding compound 176 ingresses undersemiconductor die 164 around solder bumps 168, but does not occupy area172 above window 162. Area 172 is devoid of material. Excess moldingcompound 176 is held back by dam 174, which keeps window 162 free topass maximum light.

FIG. 13 illustrates pre-molded leadframe 180 with window 182. Asemiconductor die 184 with optically active area 186 is mechanically andelectrically attached to leadframe 180 with solder bumps 188. Window 182is aligned to optically active area 186 to provide a light transmissionpath. In this embodiment, a B-stage adhesive ring 194 is disposed onwindow 182, as shown in FIG. 5a , and adheres to semiconductor die 184.Adhesive ring 194 can be pre-applied or dispensed during the process. Amolding compound 196 is disposed over leadframe 180 and semiconductordie 184. The molding compound 196 ingresses under semiconductor die 184around solder bumps 188, but does not occupy area 192 above window 182.Area 192 is devoid of material. Excess molding compound 196 is held backby ring 194, which keeps window 182 free to pass maximum light. The ring194 prevents the molding compound from blocking the light transmissionpath through window 182.

FIG. 14 illustrates pre-molded leadframe 200 with elevated window 202. Asemiconductor die 204 with optically active area 206 is mechanically andelectrically attached to leadframe 200 with solder bumps 208. A moldingcompound 212 is disposed over leadframe 200 and semiconductor die 204.The molding compound 212 ingresses under semiconductor die 204 aroundsolder bumps 208. In this embodiment, the elevated window 202, as shownin FIGS. 1c and 2c , holds back excess molding compound 212, which keepswindow 202 free to pass maximum light. The elevated portion of window202 prevents the molding compound from blocking the light transmissionpath.

FIG. 15 illustrates pre-molded leadframe 200 with elevated window 202,as described in FIGS. 1c and 2c . A semiconductor die 204 with opticallyactive area 206 is mechanically and electrically attached to leadframe200 with solder bumps 208. An underfill material 210 is disposed undersemiconductor die 204 around solder bumps 208. In this embodiment, theelevated window 202, as shown in FIGS. 1c and 2c , holds back excessunderfill material 210, which keeps window 202 free to pass maximumlight. The underfill material 210 can be epoxy, polymeric material,film, or other non-conductive material. Solder bumps 208 can be sized tocreate a gap 211 between elevated window 202 and semiconductor die 204.A molding compound 212 is disposed over leadframe 200 and semiconductordie 204.

FIG. 16 illustrates pre-molded leadframe 200 with elevated window 202,as described in FIGS. 1c and 2c . A semiconductor die 204 with opticallyactive area 206 is mechanically and electrically attached to leadframe200 with solder bumps 208. Solder bumps 208 can be sized to create a gapbetween elevated window 202 and semiconductor die 204. In thisembodiment, a clear underfill material 214 is disposed undersemiconductor die 204 and around solder bumps 208. The clear underfillmaterial 214 also creeps into the gap under semiconductor die 204. Amolding compound 212 is disposed over leadframe 200 and semiconductordie 204.

FIG. 17 illustrates pre-molded leadframe 200 with elevated window 202,as described in FIGS. 1c and 2c . A semiconductor die 204 with opticallyactive area 206 is mechanically and electrically attached to leadframe200 with solder bumps 208. In this embodiment, a clear adhesive 218 isdisposed over window 202 prior to die attach. A molding compound 212 isdisposed over leadframe 200 and semiconductor die 204. The moldingcompound 212 ingresses under semiconductor die 204 around solder bumps208. In this embodiment, the elevated window 202, as shown in FIGS. 1cand 2c , and clear adhesive 218 holds back excess molding compound 212,which keeps window 202 free to pass maximum light.

FIG. 18 illustrates pre-molded leadframe 220 with the light transmittingmaterial formed as convex lens 222. A semiconductor die 224 withoptically active area 226 is mechanically and electrically attached toleadframe 220 with solder bumps 228. The convex lens focuses light ontooptically active area 226. An underfill material 230 is disposed undersemiconductor die 224 around solder bumps 228. In this embodiment, dam232 holds back excess underfill material 230, which keeps window 222free to pass maximum light. The underfill material 230 can be epoxy,polymeric material, film, or other non-conductive material. Solder bumps208 can be sized to create a gap 234 between dam 232 and semiconductordie 224. A molding compound 236 is disposed over leadframe 220 andsemiconductor die 224.

FIG. 19 illustrates pre-molded leadframe 240 with opaque filler material242 and embedded glass 244, as described in FIG. 4a . A semiconductordie 246 with optically active area 248 is mechanically and electricallyattached to leadframe 240 with solder bumps 250. An underfill material252 is disposed under semiconductor die 246 around solder bumps 250, butdoes not occupy area 254 above window 244. Area 254 is devoid ofmaterial. The underfill material 252 can be epoxy, polymeric material,film, or other non-conductive material. A molding compound 256 isdisposed over leadframe 240 and semiconductor die 246. Molding compound256 can be made with epoxide resins, silica, cresol novolac epoxy,phenol novolac, antimony, bromide, or carbon.

FIG. 20 illustrates pre-molded leadframe 240 with opaque filler material242 and embedded glass 244, as described in FIG. 4a . A semiconductordie 246 with optically active area 248 is mechanically and electricallyattached to leadframe 240 with solder bumps 250. In this embodiment, aclear underfill material 258 is disposed under semiconductor die 246 andaround solder bumps 250. A molding compound 256 is disposed overleadframe 240 and semiconductor die 246.

FIG. 21 illustrates pre-molded leadframe 260 with elevated window 262having embedded glass 264. A semiconductor die 266 with optically activearea 268 is mechanically and electrically attached to leadframe 260 withsolder bumps 270. A molding compound 272 is disposed over leadframe 260and semiconductor die 266. The molding compound 272 ingresses undersemiconductor die 266 around solder bumps 270. In this embodiment, theelevated window 262 holds back excess molding compound 272, which keepswindow 262 free to pass maximum light.

FIG. 22 illustrates pre-molded leadframe 280 with inner and outer leadsand window 282, e.g., as described in FIG. 3. A semiconductor die 284with optically active area 286 is mechanically and electrically attachedto leadframe 280 with solder bumps 288. In this embodiment, a B-stageadhesive ring 290 is disposed on window 282, as shown in FIG. 5a , andadheres to semiconductor die 284. Adhesive ring 290 can be pre-appliedor dispensed during the process. A molding compound 292 is disposed overleadframe 280 and semiconductor die 284. The molding compound 292ingresses under semiconductor die 284 around solder bumps 288, but doesnot occupy area 294 above window 282. Area 294 is devoid of material.Excess molding compound 292 is held back by ring 290, which keeps window282 free to pass maximum light. The ring 290 prevents the moldingcompound from blocking the light transmission path through window 282.

FIG. 23 illustrates pre-molded leadframe 300 with inner and outer leadsand elevated window 302, e.g., as described in FIG. 3. A semiconductordie 304 with optically active area 306 is mechanically and electricallyattached to leadframe 300 with solder bumps 308. Solder bumps 308 can besized to create a gap between elevated window 302 and semiconductor die304. In this embodiment, a clear underfill material 310 is disposedunder semiconductor die 304 and around solder bumps 308. The clearunderfill material 310 also creeps into the gap under semiconductor die304. A molding compound 312 is disposed over leadframe 300 andsemiconductor die 304.

FIG. 24 illustrates pre-molded laminated substrate 320 and window 322,e.g., as described in FIG. 2a . A semiconductor die 324 with opticallyactive area 326 is mechanically and electrically attached to leadframe320 with solder bumps 328. In this embodiment, a B-stage adhesive ring330 is disposed on leadframe 320 around window 322, as shown in FIG. 5a, and adheres to semiconductor die 324. Adhesive ring 330 can bepre-applied or dispensed during the process. A molding compound 332 isdisposed over leadframe 320 and semiconductor die 324. The moldingcompound 332 ingresses under semiconductor die 324 around solder bumps328, but does not occupy area 334 above window 322. Area 334 is devoidof material. Excess molding compound 332 is held back by ring 330, whichkeeps window 322 free to pass maximum light. Solder bumps 336mechanically and electrically connect to lands 338 which pass throughleadframe 320.

FIG. 25 illustrates pre-molded laminated substrate 340 and window 342. Asemiconductor die 344 with optically active area 346 is mechanically andelectrically attached to leadframe 340 with solder bumps 348. Anunderfill material 350 is disposed under semiconductor die 344 aroundsolder bumps 348, but does not occupy area 352 above window 342. Area352 is devoid of material. In this embodiment, window 342 includes dam354, such as shown in FIG. 2b , to prevent the underfill material fromencroaching onto window 342. Excess underfill material 350 is held backby dam 354, which keeps window 342 free to pass maximum light. Theunderfill material 350 can be epoxy, polymeric material, film, or othernon-conductive material. Solder bumps 348 can be sized to create a gapbetween dam 354 and semiconductor die 344. A molding compound 356 isdisposed over leadframe 340 and semiconductor die 344. Molding compound356 can be made with epoxide resins, silica, cresol novolac epoxy,phenol novolac, antimony, bromide, or carbon. Solder bumps 358mechanically and electrically connect to lands 359 which pass throughleadframe 340.

FIG. 26 illustrates pre-molded leadframe 360 with window 362. Asemiconductor die 364 with optically active area 366 is mechanically andelectrically attached to leadframe 360 with bond wires 368. Bond wires368 connect by way of through hole vias (THV) 370 to contact pads 372.Bond wires 368 provide electrical interconnect for semiconductor die364, as well as other semiconductor devices or external electricalconnections. In this embodiment, window 362 includes dam 374 to preventany material from encroaching onto window 362. A B-stage adhesive ring376 is disposed on top of dams 374, as shown in FIG. 5b , and adheres tosemiconductor die 364. Adhesive ring 376 can be pre-applied or dispensedduring the process. A molding compound 378 is disposed over leadframe360 and semiconductor die 364. The molding compound 378 ingresses undersemiconductor die 364, but does not occupy area 379 above window 362.Area 379 is devoid of material. Excess molding compound 378 is held backby dam 374 and ring 376, which keeps window 362 free to pass maximumlight.

FIG. 27 illustrates pre-molded leadframe 380 and window 382, e.g., asdescribed in FIG. 2a . A semiconductor die 384 with optically activearea 386 is mechanically and electrically attached to leadframe 380 withbond wires 388. Bond wires 388 connect by way of THV 390 to contact pads392. In this embodiment, a B-stage adhesive ring 394 is disposed onwindow 382, as shown in FIG. 5a , and adheres to semiconductor die 384.Adhesive ring 394 can be pre-applied or dispensed during the process. Amolding compound 396 is disposed over leadframe 380 and semiconductordie 384. The molding compound 396 ingresses under semiconductor die 384,but does not occupy area 398 above window 382. Area 398 is devoid ofmaterial. Excess molding compound 396 is held back by ring 394, whichkeeps window 382 free to pass maximum light.

While one or more embodiments of the present invention have beenillustrated in detail, the skilled artisan will appreciate thatmodifications and adaptations to those embodiments may be made withoutdeparting from the scope of the present invention as set forth in thefollowing claims.

What is claimed:
 1. A method of making a semiconductor device,comprising: providing a semiconductor die including an optically activearea; providing a substrate including a contact pad extending from afirst surface of the substrate through an opaque perimeter region of thesubstrate to a second surface of the substrate opposite the firstsurface of the substrate; disposing a light transmitting material withinan interior portion of the substrate to create a light transmittingregion; disposing the semiconductor die over the substrate to align thelight transmitting region with the optically active area; and depositingan encapsulant over the semiconductor die and substrate, wherein anelevated area of the substrate blocks the encapsulant to maintain lighttransmission through the light transmitting region to the opticallyactive area of the semiconductor die.
 2. The method of claim 1, whereinthe elevated area of the substrate includes a dam to block theencapsulant.
 3. The method of claim 1, further including disposing theelevated area of the substrate over the optically active area of thesemiconductor die.
 4. The method of claim 1, further including disposingan optical grade material between the light transmitting region of thesubstrate and the optically active area of the semiconductor die.
 5. Themethod of claim 1, further including disposing an underfill materialaround the light transmitting region.
 6. The method of claim 1, furtherincluding forming a notch in the light transmitting region.
 7. A methodof making a semiconductor device, comprising: providing a semiconductordie including an optically active area; providing a substrate includinga contact pad extending from a first surface of the substrate throughthe substrate to a second surface of the substrate opposite the firstsurface of the substrate; disposing a light transmitting material withinan interior portion of the substrate to create a light transmittingregion; disposing the semiconductor die over the substrate to align thelight transmitting region of the substrate with the optically activearea of the semiconductor die; depositing an encapsulant over thesemiconductor die and substrate; and depositing the encapsulant over thesemiconductor die and substrate while an elevated area of the substrateblocks the encapsulant to maintain light transmission through the lighttransmitting region to the optically active area of the semiconductordie.
 8. The method of claim 7, wherein the elevated area of thesubstrate includes a dam to block the encapsulant.
 9. The method ofclaim 7, further including disposing the elevated area of the substrateover the optically active area of the semiconductor die.
 10. The methodof claim 7, further including depositing an underfill material aroundthe light transmitting region.
 11. The method of claim 7, furtherincluding disposing an opaque material around the light transmittingregion of the substrate.
 12. The method of claim 7, wherein the contactpad includes a finger extending from a dam bar for electrical connectionto the semiconductor die.
 13. A method of making a semiconductor device,comprising: providing a semiconductor die; providing a substrateincluding an elevated area of the substrate to block the encapsulant anda light transmitting region and a contact pad extending through thesubstrate between a first surface of the substrate and a second surfaceof the substrate opposite the first surface; disposing the semiconductordie over the substrate; and depositing an encapsulant over thesemiconductor die and substrate.
 14. The method of claim 13, whereinproviding the elevated area of the substrate includes forming a damaround the light transmitting region of the substrate.
 15. The method ofclaim 13, wherein providing the elevated area of the substrate includesdepositing an underfill material around the light transmitting region ofthe substrate.
 16. The method of claim 13, further including depositingan optical grade material between the semiconductor die and substrate.